It's Hot! Plutonium 238 is Back

On This Episode

Casey Dreier tells the winding tale of Plutonium 238, the radioactive isotope that is vital for exploration of the solar system. The US came dangerously close to exhausting its supply. Even with production restarted, there are major challenges facing explorers. Bill Nye reviews “Gravity,” while Emily Lakdawalla looks at what may be a budding space race between two ambitious Asian nations. Things turn spooky weird on this week’s Halloween edition of What’s Up.

Trivia Contest

This week's prize is the new and stylish Planetary Radio t-shirt.

This week's question:If you wanted to form a vocal group that sings without accompaniment, what star would you want in your group?

To submit your answer:Complete the contest entry form at http:planetary.org/radiocontest or write to us at [email protected] no later than Monday, November 4, at 2pm Pacific Time. Be sure to include your name, mailing address and shirt size.

Last week's question:Name the four known innermost moons of Jupiter, all of which are interior to the Galilean satellites, and revolve in less than an Earth day.

Answer:The answer will be revealed next week.

Question from the week before:What was the name of Scott Carpenter's Mercury spacecraft?